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PDF STLC30R80 Data sheet ( Hoja de datos )
| Número de pieza | STLC30R80 | |
| Descripción | INTEGRATED RINGING SLIC FOR SHORT LOOP APPLICATIONS | |
| Fabricantes | ST Microelectronics | |
| Logotipo |  |
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® STLC30R80
INTEGRATED RINGING SLIC
FOR SHORT LOOP APPLICATIONS
MONOCHIP SLIC SUITABLE FOR SHORT
LOOP APPLICATIONS
IMPLEMENTES ALL KEY FEATURES OF
THE BORSHT FUNCTION
INTEGRATED RINGING
SOFT BATTERY REVERSAL WITH PRO-
GRAMMABLE TRANSITION TIME
ON HOOK TRANSMISSION
LOW POWER DISSIPATION IN ALL OPER-
ATING MODES
AUTOMATIC DUAL BATTERY OPERATION
INTEGRATED RING TRIP DETECTION
METERING PULSE INJECTION
LOOP START, GROUND START FEATURES
SURFACE MOUNT PACKAGE
-40 TO +85°C OPERATING RANGE
DESCRIPTION
The STLC30R80 is a SLIC device suitable for
short loop applications. The SLIC provides the
BLOCK DIAGRAM
TQFP44 (10 x 10)
ORDERING NUMBER: STLC30R80
generation of the ringing signal and the standard
battery feeding with full programmability of the DC
characteristic.
In particular two external resistors allow to set the
limiting current value (up to 50mA) and the value
of the resistive feeding when not in constant cur-
rent region.
D2 D1 D0
CRT RT1 RT2
DET
GDK/AL
CSIN
CSOUT
RES
SW
TTXIN
ZB
TX
RX
LINE STATUS
LOGIC
INTERFACE
&
DECODER
COMMANDS
SUPERVISION
ILT
LINE
ILL INTERFACE
AC
PROCESSOR
REFERENCE
&
BIAS SWITCHING
AC+
DC
AC +
DC
DC
PROCESSOR
TIP
RING
BGND
VREG
ILTF
RLIM
RTH
ZAC1 ZAC RS CAC IREF VCC VDD AGND CREV CSVR VBAT BASE RDC D99TL431AMOD
November 2001
1/13
1 page  
STLC30R80
Concerning AC characteristic the STLC30R80 al-
lows to set 2W termination impedance by means of
one external scaled impedance that may be com-
plex. Two to four wire conversion is provided by an
external network. Such network can be avoided in
case of application with COMBOII, in this case the
two to four wire conversion is implemented inside
the COMBOII by means of the programmable Hy-
bal filter.
When in ACTIVE mode it is also possible to per-
form battery reversal in soft mode (with program-
mable transition time) without affecting the AC sig-
nal transmission.
Ringing
When ringing mode is selected, by toggling the
D2 pin is possible to insert the ringing signal on
the line: the ringing frequency is equal to the one
applied to the D2 pin. The ringing signal is a bal-
anced trapezoidal wave form where the TIP and
RING voltages switch continuously between GND
and VREG: VREG is obtained directly from VB1
(VREG = VB1 - 1.8V). The slope of the trapezoi-
dal wave form is set by the external Crev capaci-
tor and it allows to obtain ringing signal with dis-
tortion less than 10%: with a fine tuning of this
capacitor is possible to obtain distortion value
less than 5% (crest factor from 1.25 to 1.35).
Figure c. Typical ringing wave form.
GND
TIP
3V typ.
dV/dT set
by CREV
RING
VREG
3V typ.
60V
typ.
The VB1 value must be higher enough (~70V) in
order to obtain ringing signals with more than
40Vrms. The VB2 battery is used only when the
line is in off hook and its value can be reduced
(typ. 24V) in order to minimize the power con-
sumption.
The ring trip detection is performed sensing the
variation of the AC line impedance from on-hook
(relatively high) to off-hook (relatively low). This
particularly ring trip method allows to operate
without DC off-set superimposed on the ringing
signal and therefore obtaining the maximum pos-
sible ring level on the load starting from a given
negative battery.
It should be noted that such a meted is optimized
for operation on short loop applications and may
not operate properly in presence of long loop
(>500 Ohm).
As the ring trip is detected the logic indicator DET
is set low and the ringing is automatically discon-
nected without waiting for the card controller com-
mand (auto ring trip).
Ringing with high REN number
When ringing high number of REN, for example
5REN, or short loops, it could happen that the line
AC current, trigger the ring trip circuit producing
false ring trip.
If this happens, a proper SW resistor (Rswitch)
can be inserted between RLIM and the pin.
The effect of this resistor is to improve the AC
current capability in Ring mode avoiding false ring
trip in presence of high REN numbers (typ.
5REN) and short loop.
One side effect of Rswitch is to reduce ring trip
sensitivity in presence of long loops; therefore it is
recommended to adjust Rswitch properly check-
ing the correct behaviour of the device in the two
worst-case conditions:
- 0Ω loop, Max REN#
- Max loop length, 1 REN
The lower is the Rswitch value; the higher is the
immunity to false Ring trip, producing as side ef-
fect a lower Ring trip sensitivity on long loops.
The typical value of Rswitch is shown in the Ex-
ternal Components Table (pag.7.13)
High Impedance Feeding.
As Stand-By, this mode is set in On-Hook condi-
tion, with further reduced power consumption.
Higher power efficiency turns back a lower immu-
nity of the Off-Hook detector to line common
mode currents. The DC feeding shows a constant
current characteristic (Ilim = 17mA) followed by a
resistive range with an equivalent series resis-
tance RFEED = 1600Ω + 2Rp.
Thermal protection circuit is still active, preventing
the junction temperature, in case of fault condi-
tion, to exceed 150°C
In High Impedance Feeding most of the circuit is
switched off, only the circuit, dedicated to Off-
Hook detection, is powered. This allows to reduce
Figure d. STLC30R80 DC Characteristic in
High Impedance Feeding
I
17mA
RFEED = 1600Ω +2RP
D98TL373
V
VBAT -0.8V
5/13
5 Page 
STLC30R80
APPENDIX A
Battery voltage autoset
The STLC30R80 shows a line voltage depending on the voltage applied to Vbat pin. In particular in the
On-Hook the line voltage is Vbat if the SLIC is put in HI-Z mode or Vbat -7.8V if the SLIC is put in Active
mode.
If the battery voltage applied to the Vbat pin is always -70V (necessary to generate the proper ringing
signal), during the On-Hook the line voltage is higher than 60V.
A simple circuit to generate the proper Off-Hook battery voltage can be used starting from the -70V as
shown in the below figure A1.
The RING command (active low) is used to switch on the NPN transistor and apply the battery voltage
directly to the Vbat pin. When the RING command is high the NPN transistor is off and the zener diode
reduces the voltage applied to the Vbat pin.
Figure A1.
VCC
RING
470KΩ
47KΩ
BC556
68KΩ
BC558
470KΩ
VBAT
24V
STLC30R80
D00TL461
BATTERY VOLTAGE (-70V)
11/13
11 Page | ||
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